1. Field of the Invention
The present invention relates to a forming process, especially to a process for forming a hollow member with a complicated cross-section, associated with a field of industrial manufacture.
2. Description of Background Art
As energy crisis and environmental problem become increasingly prominent, automobile lightening is receiving more and more attention. The hydroforming process is just put forward under this background, and has been widely utilized to form a hollow member with complicated cross-section of a motor vehicle. The hydroforming process is to make a tube blank inside a die expand to be in close contact with the inner surface of the die by applying a very high internal pressure to the inside of the tube blank, and to thereby form a hollow member with a complicated cross-section. However, in practice, this process has the following disadvantages leading to a high production cost: 1) relying heavily on an ultrahigh pressure generator; 2) forming pressure required reaching up to more than one hundred MPa, even up to hundreds of MPa for some members with sharp edges, which would greatly decrease the production efficiency due to the long feedback time of ultrahigh pressure; and 3) requiring a very large equipment due to the high forming pressure.